Injuries to tissue, such as cartilage, skin, muscle, bone, tendon, and ligament where the tissue has been injured or traumatized frequently require surgical intervention to repair the damage and facilitate healing. Such surgical repairs can include suturing or otherwise repairing the damaged tissue with known medical devices, augmenting the damaged tissue with other tissue, using an implant, a graft or any combination of these techniques. Despite these conventional methods of tissue repair, there continues to be a need for surgical solutions that facilitate the regeneration of new, healthy tissue to provide more reliable repair and healing of the injured or damaged tissue over the long term.
The search for a reliable source of viable cells for tissue regeneration has been pursued for years. Recent tissue engineering techniques for repairing tissue have typically involved replacing or reconstructing damaged or injured tissue with cells that have been manipulated ex vivo to stimulate new tissue growth. The cells are usually incorporated into a delivery vehicle (e.g., a scaffold or surgical implant) for placement at the tissue site, whereupon new tissue can be grown. Various surgical implants are known and have been used in surgical procedures to help achieve these benefits. For example, it is known to use various devices and techniques for creating implants having isolated cells loaded onto a delivery vehicle. Such cell-seeded implants have been used in an in vitro method of making and/or repairing cartilage by growing cartilaginous structures that consist of chondrocytes seeded onto biodegradable, biocompatible fibrous polymeric matrices as well as matrices developed from collagenous materials. Such methods require the initial isolation of chondrocytes from cartilaginous tissue prior to the chondrocytes being seeded onto the polymeric matrices. Other techniques for repairing damaged tissue employ implants having stem or progenitor cells that are used to produce the desired tissue. For example, it is known to use stem or progenitor cells, such as the cells within fatty tissue, muscle, bone marrow, or embryonic tissue to regenerate bone, cartilage, and other soft tissues in a patient. For example, stem cells from fat are removed from the patient and placed in an environment favorable to cartilage formation, thereby inducing the cells to proliferate and to create a different type of cell, such as cartilage cells.
While the trend towards using tissue engineering approaches to tissue repair continues to gain popularity, mainly because of the long-term benefits provided to the patient, these current techniques are not without drawbacks. One disadvantage with current tissue engineering techniques is that they can be time consuming. A typical process involves the harvest of a tissue sample from the patient in a first surgical procedure, which is then transported to a laboratory for cell isolation, culture and amplification. The cell sample is grown for a period of 3 to 4 weeks using standard cell culture techniques to create a cell bank. Once the cell population has reached a target number, the cells are sent back to the surgeon for implantation during a second surgical procedure. This manual, labor-intensive process is extremely costly and time consuming. Although the clinical data suggest long-term benefits for the patient, the prohibitive cost of the procedure, combined with the traumatic impact of two surgical procedures, has hampered adoption of these techniques.
One method for tissue repair has been to place into a defect site an implant that is composed of cultured and amplified cells and a scaffold, which provides structural integrity and a surface area for cell adhesion and proliferation. In the past, such scaffolds have consisted mostly of two- or three-dimensional porous scaffolds that allow cell invasion and remodeling once the scaffold has been combined with living cells and has been delivered inside the patient. This model is limited in application because of the secondary surgery and high costs involved. And though allografts have been used for tissue repair in the past, this solution is also not ideal because of the limited availability of graft material and the potential for disease transmission.
For these reasons, there continues to exist a need in this art for novel devices and methods for regenerating tissue which are less time consuming and easier to implement. It is also desirable to provide an implant which can serve as a reliable source of viable cells, and which can be made in a quick and efficient manner for immediate use during surgery. There is thus a need for a less costly solution to repairing tissue defects or injuries that also provides the advantages of tissue regeneration, without the encumbrances of the currently available devices and methods of tissue repair previously mentioned.